In recent years, magnetic disk drives (HDDs) have been widely used not only with computer devices but also with household electric appliances, such as video recorders. Such a magnetic disk drive includes a magnetic disk and a magnetic head slider. While flying over the magnetic disk, the magnetic head slider magnetizes the magnetic disk or reads a magnetized state of the magnetic disk and thereby executes recording or playback of information, for example, in writing information, as the distance between the magnetic disk medium and the magnetic head slider becomes narrower, expansion of a magnetic filed formed by the magnetic head can be reduced to the smaller, whereby the area size to be magnetized on the magnetic disk drive, the distance between the magnetic disk medium and the magnetic head, that is, the fly height of the magnetic head slider is south to be reduced.
As one of conventional techniques for reducing the fly height of the magnetic head slider, a technique is known in which a heater formed from a thin film resistor or the like is mounted in the vicinity of a recording/playback element. A part of the magnetic head slider is heated and thermally expanded to thereby bring the recording/playback element to be close to the side of the magnetic disk. In this case, the fly height of the magnetic head slider varies depending upon any one of operating conditions, such as operating environment temperature, operating environment pressure, zone of a magnetic disk medium targeted for recording/playback, and operation modes such as recording and playback modes. As such, the amount of heating of the heater has to be control corresponding to the respective operating condition.
To deal with the operating environment temperature, currently available magnetic disk drives include a type including a temperature sensor and hence capable of measuring the temperature by using the temperature sensor. Japanese Patent Publication No. 2006-164388 discloses a method of determining the amount of application power to the heater corresponding to the operating environment temperature by using output information received from a temperature sensor such as described above.
Pressure (air pressure) varies corresponding to the altitude at which a magnetic disk drive is used, whereby the fly height of a magnetic head slider being lifted by the power of air is varied. A similar phenomenon takes place even in a spacing, such as the interior of an aircraft, which is hermetically enclosed by a pressure different from the standard atmospheric pressure, irrespective of the altitude. While general types of presently commercially available magnetic disk drives do not include an air pressure sensor, various absolute-pressure dedicated types of air pressure sensors are commercially available. In a magnetic disk drive using such air pressure sensor, output information from the air pressure sensor can be utilized to control the power for application to the heater, thereby making possible the appropriate maintenance of the fly height of the magnetic head slider.
In this case, an important issue is how to mount the air pressure sensor in the magnetic disk drive. Simple assembly of the existing air pressure sensor into the drive requires an additional spacing for accommodating the sensor. Further, costs for the sensor itself and mounting it increase the cost of the overall magnetic disk drive. Further, a final configuration of the magnetic disk drive inevitably become more complex than that in the existing configuration, consequently increasing concern in reliability over causes of failure, for example.